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D E Cadwallader

Publications and source records attributed to D E Cadwallader.

10 recordsLinked to original sources
PubMed1989

Stability of pibenzimol hydrochloride in commonly used infusion solutions and after filtration.

The stability of pibenzimol hydrochloride was evaluated after reconstitution, after addition to several intravenous fluids, and after filtration. Vials containing pibenzimol hydrochloride 50 mg were reconstituted with 2.5 mL of 0.9% sodium chloride injection to 20 mg/mL. For determination of drug stability in intravenous fluids, vial contents were further diluted to 0.15 mg/mL by injection into glass containers and polyvinyl chloride (PVC) bags containing 250 mL of 5% dextrose injection, 0.9% sodium chloride injection, or lactated Ringer's injection. Pibenzimol concentrations were determined immediately after preparation and at various intervals after storage at 4-6 degrees C or 25 degrees C by means of a stability-indicating, high-performance liquid chromatographic technique. Vial contents were inspected visually for color changes, and pH was measured. Determinations were also made of the stability of pibenzimol 0.15 mg/mL in 0.9% sodium chloride injection after simulated infusions using a 0.22-micron filter set at 25 degrees C. All study solutions and admixtures retained more than 90% of the initial pibenzimol concentration. The greatest loss of drug (6-7%) occurred after 24 hours in lactated Ringer's injection in both glass and PVC containers and in 0.9% sodium chloride injection in PVC bags. No drug loss occurred as a result of filtration. Reconstituted pibenzimol hydrochloride and admixtures of pibenzimol in 5% dextrose injection, 0.9% sodium chloride injection, or lactated Ringer's injection in glass or PVC containers are stable for at least 24 hours at 25 degrees C. Filtration has no effect on stability.

Benzimidazoles↗
PubMed1978

Automated potentiometric procedure for studying dissolution kinetics acidic drugs under sink conditions.

An automated potentiometric procedure was used for studying in vitro dissolution kinetics of acidic drugs. Theoretical considerations indicated that the pH-stat method could be used to establish approximate sink conditions or, possibly, a perfect sink. Data obtained from dissolution studies using the pH-stat method were compared with data obtained from known sink and nonsink conditions. These comparisons indicated that the pH-stat method can be used to establish a sink condition for dissolution studies. The effective diffusion layer thicknesses for benzoic and salicylic acids dissolving in water were determined, and a theoretical dissolution rate was calculated utilizing these values. The close agreement between the experimental dissolution rates obtained under pH-stat conditions and theoretical dissolution rates indicated that perfect sink conditions were established under the experimental conditions used.

Autoanalysis↗
PubMed1976

Effects of various hydrodynamic conditions on dissolution rate determinations.

An automated potentiometric procedure was used in dissolution rate studies to determine the effects of various hydrodynamic conditions on dissolution rate determinations. Changes in the hydrodynamics of the system resulted from using various sizes and shapes of dissolution vessels. Dissolution rate constants for benzoic acid prills in distilled water at pH-stat 6.2 were used as a measure of the agitation intensities present in the different shaped vessels. Great variations in the dissolution rates occurred in vessels with the same diameter and stirrer blade position when the shapes of the bottom of the vessel were varied. A similar order of dissolution rates was obtained at 100 and 150 rpm for the individual vessels at various propeller heights. The order differed from one vessel to another, depending on the shape of the bottom (concave, convex, or flat) of the vessel. In some cases, a change in the type of bottom resulted in the opposite order of rates for vessels with the same diameter.

Benzoates↗
PubMed1976

Nitrofurantoin solubility in aqueous urea and creatinine solutions.

Experiments were carried out to determine the effect of urea and creatinine on the solubility of nitrofurantoin in water at different temperature and pH conditions. The addition of urea to aqueous media increased nitrofurantoin solubility up to a maximum concentration level and then decreased solubility at higher urea concentrations. The amount of urea needed to bring about maximum nitrofurantoin solubility was dependent on temperature and ranged between 1.75 and 2.50%. Spectral studies suggest a possible interaction between urea and nitrofurantoin molecules. Nitrofurantoin solubility increased with an increasing creatinine concentration ranging from 0.05 to 1.6%. Spectral studies indicate a strong interaction between creatinine and nitrofurantoin molecules in solution. The combined effect of urea and creatinine of the solubility of nitrofurantoin could account for the absence of crystalluria with this drug, even though unusually high concentrations in urine have been reported.

Buffers↗
PubMed1975

Behavior of erythrocytes in ternary solvent systems.

The effect of ternary solvent systems on erythrocytes was investigated. Hemolysis experiments were run at 37degree in solutions containing various amounts of water, two nonaqueous solvents, and 0.9% sodium chloride. The nonaqueous solvents were propylene glycol, polyethylene glycol 400, dimethyl sulfoxide, dimethylformamide, and tetramethylurea. Ternary diagrams based on the critical hemolytic compositions of the various ternary systems are presented.

Adult↗
PubMed1975

Nitrofurantoin.

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Biological Availability↗